I started breastfeeding and only

pumped 1 oz this morning. I go back to pump again and can’t even get enough milk to fill the bottle of the bottle after pumping each breast for 20 mins. I don’t know what I’m suppose to do bc nothing I’ve tried seems to help my supply. I also can’t get baby to feed from me, she’ll latch for maybe 30 seconds and then start screaming so I always end up giving her formula. I have an appointment with a lactation consultant next week but I’m feeling frustrated. please help!